In order to improve convenience of users when luggage is put into a luggage space at a rear side of a vehicle through a back door at a back surface side of the vehicle, a kick sensor is provided at a rear part of the vehicle. The kick sensor is a sensor which detects that the user has stuck out a foot tip to a lower side at the rear part of the vehicle, and, when the user approaches the back door in a closed state while carrying the luggage and sticks out the foot tip to the lower side of the vehicle, the kick sensor detects the sticking-out movement, and controls a back door opening/closing unit, so that the back door is automatically opened.
JP 2015-021238 A discloses provision of a kick sensor of a two-stage structure having an upper electrostatic sensor and a lower electrostatic sensor which extend in a width direction of the vehicle, at an inner side of a rear bumper cover of the vehicle. In this structure, for example, the lower sensor comprises three sensor parts placed in the width direction of the vehicle, and a spacing between adjacent sensor parts is set to 10˜20 cm, which is about a typical width size between the feet of a human, to reduce possibility of erroneous detection of the foot tip of the user.
When the kick sensor for opening and closing the back door is provided inside the rear bumper cover, if foreign objects such as soil, rain, snow, or the like enter during traveling of the vehicle, an erroneous operation may occur. In consideration of this, there is desired a lower structure of a vehicle which suppresses entrance of the foreign objects into a placement region of the kick sensor, to thereby prevent the erroneous operation.